The present invention relates to footwear, and is concerned in particular with the shoes, boots, and overshoes which contain toe caps that structurally reinforce the toe of the footwear and protect the wearer from injury caused by objects which fall or roll onto the toe.
Shoes, boots, and other footwear with internal toe caps for structural reinforcement are old in the art and have been sold commercially for many years. Such footwear is worn by industrial workers, firemen, lumberjacks, military personnel, and many other people who work in environments where the potential for injury to the foot due to heavy objects is relatively high. Until recently, all toe caps have been made from metal, specifically steel, because the greatest strength could be derived from such a material in limited wall thicknesses.
Several constraints are imposed on the design of the toe cap and necessitate a shell-like structure. First of all, the cap must be hollow in order to envelop the toes of the wearer in a protective pocket, and the hollow pocket of the cap must have the same approximate volume and shape as an ordinary shoe in the toe area for fit and comfort. Furthermore, for reasons of comfort and practicality, the toe cap must be lightweight, and for practicality and esthetics, the toe cap should fit within the general contours of a shoe toe.
More recently, non-metallic toe caps made of plastic have appeared on the market in place of the steel toe caps of the prior art. Plastic toe caps offer a number of advantages over steel caps. Plastic toe caps are lighter in weight which results in less fatigue to the wearer during extended periods of use. Plastics also have much lower heat conductivity, and therefore they offer much more comfort to the wearer in cold weather and reduce the danger of frostbite.
Plastics in general are not ductile, and as a result, when they are stressed beyond their limits, they flex first to a limited degree and then fracture. When the load or weight is removed from the safety shoe, the toes of the wearer are immediately freed from the stress.
Metal, on the other hand, when stressed beyond its yield point, permanently deforms with or without some fracturing, and in a safety shoe such permanent deformation and any crushing effect upon the toes is not reversed when the object or other load which caused the deformation is removed. In such a situation, the steel toe caps make removal of the shoe difficult and raise the possibility of further pain and suffering.
Plastic toe caps are also nonmagnetic and can be rendered electrically conductive or nonconductive as desired. Plastic caps do not corrode and hence are not affected by moisture and perspiration.
A primary concern when a steel toe cap is replaced by plastic is the adequacy of the structural reinforcement since substantially all plastics have tensile and compressive strengths that are less than those for steel. Recognized standards exist both in the United States and foreign countries for testing and acceptance of toe caps. In the United States, the toe caps must meet compression and impact tests according to ANSI Standard Z41-1983, of the American National Standards Institute, New York, N.Y. In Europe, toe caps are tested for impact resistance according to DIN Standard 4843. Prior to the development of the toe cap of the present invention, it is believed that no plastic toe cap produced on a commercial scale complied with such standards. It is accordingly an object of the present invention to provide a plastic toe cap for footwear which provides all of the recognized advantages of plastic toe caps in a design that is capable of meeting the applicable strength standards.